Coal stoker



Nov. 19, 1935.

O. W. SAVAGE El AL COAL STQKER Filed Sept. 18, 1955 2 sheets-sheet 1arn/v.4 E Y 5414465 SQ ATTORN N 1935- o. w. SAVAGE El AL COAL STOKER I 2Sheets-Sheet 2 Filed Sept. 18, 1933 lllilll I Patented Nov. 19, 1935COAL STOKER Oscar W. Savageand Stanley Savage, Seattle, Wash.

Application September 18, 1933, Serial No. 689,869

' 2 Claims. (01. 110-109) This invention relates to improvements in coalstokers, and it has reference more particularly to stokers especiallydesigned for use in combination with furnaces of the common typesemployed for residence heating, although it is to be understood thatthey are not limited to this particular use since they may be employedwith entire satisfaction for other and various power and heatingpurposes.

It is the principal object of the present invention to provide acomparatively inexpensive stoker of a durable, efiicient andsatisfactory character; that is simple in construction; easilyaccessible for adjustment, cleaning or repair, and

so designed that it may be readily installed in furnaces of the ordinarytypes without requiring any material alteration in the structure of thefurnace to receive and accommodate the stoker grates.

It is also an object of this invention to provide a coal stoker of thecharacter above stated, whereby fine coal is forced, under definitecontrol, from a supply hopper and through a tube leading to the stokergrates, by the reciprocal action of a feed plunger operating inconjunction with a movable plate forming the bottom wall of the tube,which plate is reciprocally actuated by the plunger in a manner wherebyclogging of the tube is avoided and the coal fed easily to the grateseven when the finest of coal is used.

It is also an object of the invention to provide for a controlledfeeding of coal by definitely regulating the effective reciprocal strokeof the plunger.

Another object of the invention resides in the provision of means forautomatic delivery of ashes from the furnace to a position for easyremoval.

Still another object is to provide a controlled,

forced delivery of air to the fire box through the stoker tube in amanner to effect complete and satisfactory combustion of fuel.

Other objects of the invention reside in the details of construction ofthe various parts; in

their combination and mode of operation as will hereinafter be fullydescribed.

In accomplishing these objects of the invention, we have provided theimproved details of construction, the preferred forms of which areillustrated in the accompanying drawings,

wherein Fig. 1 is a longitudinal, sectional view taken in a verticalplane, of a coal stoker embodying the present invention.

Fig. 2 is a diagrammatic sectional detail illustrating an alternativeconstruction asapplied to the ash removing parts.

Fig. 3 is a top, or plan view of the stoker; the hopper and motor beingremoved and the stoker tube being shown in horizontal section for pur- 5pose of better illustration.

Fig. 4 is a view, with parts omitted showing the plunger operatingmechanism and means for effecting adjustment in the efiective length ofthe plunger stroke." 10

Fig. 5 is a side view of the stoker as applied to a furnace.

Fig. 6 is a cross section of the stoker tube as seen on line 6-- 6 inFig. 3.

Fig. 7 is a diagrammatic outer end elevation of 15 the stoker.

Referring more in detail to the drawings- The present stoker, as hereinillustrated, is designed especially for use in combination with theusual types of residence heating furnaces 20 such as that designated byreference character i in Fig. 5, which has the usual ash door opening 2located below the usual firing door 3, making it possible to install thestoker simply by removing the usual coal grates from within the 25furnace, and the door from the ash opening, then projecting the gratecasting at the end of the stoker tube into the furnace through the ashdoor opening as clearly shown in Figs. 1 and 5.

The stoker embodied by this invention, briefly 80 described, consists ofa cast metal housing 5 fastened securely to the outer end of the stokertube 6, which tube in turn is fastened securely to the stoker gratehousing I. A coal supply hopper 8 is mounted on the tube and feeds coal,by 35 gravity fiow, to the tube and the coal is advanced in the tubeonto the grate bars within the grate housing 1.

As will be readily seen by reference to Figs. 1 and 6 of the drawings,the coal delivery tube 6, 40 or what has previously been referred to asthe stoker tube, is divided by a horizontal partition plate i0 intoupper and lower longitudinal passages; the top passage I i being for thepassage of coal from the hopper to the stoker grates and 45 the lowerpassage I! being for feeding of air to aid combustion. The plate in issupported for reciprocal movement in the tube by bars, or strips I3-i3'fixed to opposite side walls of tube 6, and at its inner end itslidingly overlaps a horizontal partition wall 13 within the grate barhousing land at its outer end it rests slidingly upon a transverse,vertical wall I4 that closes the outer end of the air delivery passageas seen in Fig. l. 55

Reciprocally contained in the outer end portion of the tube 6, withinthe coal delivery passage H, is a coal feeding plunger 15 having-anoutwardly extending shank l6 passing through an opening IS in a wall ofhousing 5 and connected with a cross head l1 that is reciprocallyslidable between guide rails 18-18 formed on a cross plate l9 fixedwithin the housing 5.

Revolubly mounted in vertically alinecl bearings 20-20 formed in thebottom wall of the housing 5 and on the plate 19, respectively, is ashaft 22 which has a worm gear wheel 23 fixed thereon between thebearings. A worm shaft 24 is mounted horizontally in bearings 25 in thevhousing 5, as seen in Fig. 3, and has a worm 26 in driving mesh with theworm gear 23. The shaft 24 has one end extended to the outerside ofhousing 5 and is equipped with a belt pulley 21. An electric motor 30 isfixed upon the housing 5 and this is equipped with a belt pulley 3| witha belt 32 operatingthereover and about pulley 21 to drive the shaft 24.

Fixed on the upper end of shaft 22, just above .plate 19, is a wheel 35and mounted on the wheel by an eccentrically located stud 36 is a roller31. This roller is disposed between the cross head 11 and acooperatively arranged cross head 38 that is reciprocally mounted by theguide rails l8-l8 and is connected with the cross head i1 by anadjusting screw 40.

As will be observed best by reference to Figs. 1 and 4, the screw 40 isrotatably mounted in cross head 38 but is held against longitudinalmovement relative thereto by a hand wheel M at its outer end and acollar 12 engaging the opposits side of the cross head. The inner endportion of the screw is threaded through the cross head i1. Therefore,it is apparent that by turning this screw, the cross heads i1 and 38 maybe adjusted toward or from each other.

Should it be desired to obtain the maximum stroke of the plunger forfeeding coal to the furnace, the screw 40 is manipulated to draw the twocross heads closely against opposite sides of the roller 31. Then, asthe wheel 35 rotates, the rotary motion of the eccentric roller istranslated. to reciprocal movement of the plunger. Should it be desiredto lessen the effective stroke of the plunger, the cross head 38 ismoved away from cross head l1, as seen in Fig. 1, to permit a certainamount of lost motion in the driving action of the roller. The outwardmovement of the plunger will thereby be lessened in accordance with theincrease of space between the roller 31 and the cross head 38, at thecompletion of the inward stroke. By reason of the fact that there is norelative adjustment between cross head I1 and the plunger I5, the inwardlimit if movement of the plunger will always be at the same place, butits outward stroke will depend on the closeness with which the crosshead 38 is adjusted to cross head 11.

When the plunger is reciprocally actuated inwardly to its limit oftravel by roller 31 acting on cross head 11, its forward surface will beflush with the inner edge of the hopper opening. When the plunger isretracted by roller I1 acting against cross head 38, the coal feedsdownwardly from the hopper to fill in the space vacated by the plunger.Then on its forward action, the plunger pushes the coal forwardly alongthe passage I l to the grates. It is apparent that the rate of feedingof coal may be very accurately and definitely determined by the settingof. the cross head 38 relative to cross head" thereby to regulate theextent of the stroke of the plunger in its outward travel.

Heretofore, it has been observed that coal stokers employingreciprocating plungers for feeding fine coal through a tube to thestoker grates, 5 were unsatisfactory because of the tendency of the coalto pack in the tube. Apparently, the plunger had a pulverizlng action onthe coal that was detrimental to easy feeding. Therefore, in the presentinstance we have provided the mov 10 ably mounted bottom plate I0 forthe passage II and we effect a reciprocal action of this plate inaccordance with forwarding action of the plunger so that the coal in thepassage is bodily moved along the entire length of the passage and 15 isthereby relieved of that pulverizing pressure of the plunger that wouldtend to pack it. To effect this movement of the plate 10, a cross piece50 is fixed on the plate near its outer end, and this has a verticalflange 5| extending into a re- 20 cess 52 formed in the under edge ofthe shank iii of the plunger. The length of the recess is such that itprovides a lost motion connection whereby the movement of the plate 10is of lesser extent than the plunger movement. How- 25 ever, on everyoutward movement of the plunger, the inner end of the recess engages theflange 51 to pull the plate outwardly, and on each inward movement ofthe plunger the outer end of the recess engages the flange to push theplate 30 inwardly. The combined actions of the plunger and plateprovides a very easy feeding of coal and thereby makes possible use of amotor of lesser power than otherwise would be necessary.

The grate housing 1 consists of a casting 35 formed with opposite sidewalls 10-10, a top wall 1| covering its outer end portion, a lower wall12 and the previously mentioned horizontal partition wall 13 extendingfrom the outer end of the casting a short distance inwardly. The 40hopper tube 6 is joined with the outer end of this casting so that thecoal passage ll registers with the open space between the side walls10-10 and the top and partition walls 1| and 18. The

inner end of plate 10 flatly overlies the wall 13. 45

the opposite side walls 10-10 of the casting, 55

and, as it burns, it is pushed successively from one grate bar to thenext lower one and finally the ashes are pushed over the end of thegrate into the lower part of the housing for removal, as presentlydescribed.

The grate bars ID are transversely corrugated and are arranged inoverlapped relation and in a manner whereby the corrugations cooperateto provide air spaces between the bars for delivery of air through thegrate to the top side as an aid to combustion. Also, there are airpassages 18 leading upwardly at opposite sides of the casting from theair space below the grates and these open at their upper ends intohorizontally directed channels 19, in the under surface of the 7 topwall 1 I.

Air is delivered forcibly into the air channel I! at the outer end ofthe stokertube I by menu a blower fan ofatandard entirety at I.

from and is coaxial of the motor 30, as seen in Fig. 7, and has itsshaft driven directly by the motor and an air delivery tube 82 from thefan housing leads into the air channel H through a side opening 83 ofthe latter as seen in Fig. 1. Thus air supplied under pressure by thefan is forcibly delivered along the channel l2 and through the gratebars and through the passages 18-19 to the fire to effect completeandsatisfactory combustion. The amount of air admitted is regulated byopening or closing a damper plate 85 overlying the air intake opening 86of the fan housing 80 and thus the rate of burning may be retarded orquickened as desired.

Attached to the under side of the grate bar housing is a forwardlydirected tube 90, the bottom wall of which is extended to the inner endof the casting l to catch the ashes which fall from the grates. An endgate 9| is disposed across the inner end of the casting I, pivotallysuspended by a cross rod 92 and connected pivotally at its lower edge,as at 93, to a link 9 which extends forwardly and is pivotally connectedat its outer end by a pin or bolt 95 to a crank arm 96 fixed on thelower end of the driven shaft 22. Thus, with each rotation of shaft 22,the gate 9| is swung rearwardly and then forwardly and pushes the ashesforwardly along the tube 90 to the outer end for delivery into a pan orpit at the outside of the furnace. In this arrangement the reciprocaland also oscillating action of the link in the tube keeps the ashesloosened or agitated so that packing in the tube does not occur.

As a detail of construction, the outer end of the stoker is supported bya two piece adjustable leg 98 as seen in Fig. 7, bolted to the casting5. This has a roller 99 at its lower end to facilitate shifting thestoker into or from the furnace.

In Fig. 2 we have shown an alternative construction as applied to theash tube. In this arrangement, a plate I is reciprocally movable on thebottom wall of the tube and is connected pivotally at IM with the link94. At its inner end the plate has an operating connection at I03 withthe gate 9|.

With the stoker constructed and installed as described, it is quiteapparent that the coal will feed by gravity into the stoker tube andthat it will be advanced by the combined reciprocal action of theplunger and plate It, and fed in regulated amounts dependent upon theadjustment of cross head 38 with respect to cross head l1; the rate ofcoal delivery being governed by the efl'ective stroke of the plunger.

Such devices are relatively inexpensive; are

easy to install; may be accurately regulated and will deliver the ashesto the outside of the furnace.

As a feature of construction, the ash removing means is so connectedwith the drive shaft 22 that its operating stroke will alternate withthe coal forwarding stroke of the plunger, thus to avoid any overload onthe motor and make possible use of a motor of less power.

Another feature of this construction is to be found in the lost motionconnection between the coal feeding plunger l5 and the feed plate It. Itis apparent by reference to Fig. 1 that when the plunger l5 starts onits outward movement, coal will be admitted from the hopper to fill inthe space vacated by the plunger. This space is filled to a certainextent before the plate It starts on its outward movement. This isimportant for the reason that should the plate It start to moverearwardly with the plunger, it would be apt to carry coal in the tube 6rearwardly and there would not be a desired downward feeding action fromthe hopper.

Stokers of this character are satisfactory for various heating and powerproducing purposes other than general residence heating, and while it isbelieved to contain various novel features in general construction, itsmost important features reside in the combination of reciprocatingplunger and feed plate I0 whereby easy feeding of coal is made possibleby the plunger and plate action.

Having thus described our invention, what we claim as new therein anddesire to secure by Letters Patent is- 1. A coal stoker comprising a.grate housing, a feed tube comprising air and coal delivery pas- 86sages leading into the grate housing, said passages being separated by ahorizontal feed plate adapted to support the coal in the coal passage, ahopper arranged to feed coal by gravity flow into the coal passage,means for effecting a forced delivery of air into the air passage, 2.plunger reciprocally movable in the coal passage to control admittancethereto of coal from the hopper and to effect its advancement within thetube to the grate housing, and means for eflecting reciprocal action ofthe plunger and of the plate to cooperate in the advancement of coalalong the passage.

2. A device as in claim 11 wherein the plunger has a longitudinal slot,and an abutment is fixed to the plate and extended into theslot in theplunger thereby providing a lost motion connection and delayed movementsof the plate with respect to those of the plunger.

OSCAR W. SAVAGE. STANLEY SAVAGE.

